Coexisting normal and intruder configurations in $^{32}$Mg

TL;DR

This study uses advanced in-beam spectroscopy with two reaction probes to explore the complex coexistence of normal and intruder configurations in $^{32}$Mg, providing an updated level scheme and insights into its nuclear structure.

Contribution

It introduces a novel experimental approach combining two reaction probes to better understand the coexistence of configurations in $^{32}$Mg and refines the nuclear level scheme with new spin-parity assignments.

Findings

Revealed coexistence of different nuclear structures in $^{32}$Mg.

Provided an updated level scheme with new spin-parity assignments.

Highlighted discrepancies between experimental data and theoretical models.

Abstract

Situated in the so-called "island of inversion," the nucleus $^{32}$Mg is considered as an archetypal example of the disappearance of magicity at $N=20$. We report on high statistics in-beam spectroscopy of $^{32}$Mg with a unique approach, in that two direct reaction probes with different sensitivities to the underlying nuclear structure are employed at the same time. More specifically, states in $^{32}$Mg were populated by knockout reactions starting from $^{33}$Mg and $^{34}$Si, lying inside and outside the island of inversion, respectively. The momentum distributions of the reaction residues and the cross sections leading to the individual final states were confronted with eikonal-based reaction calculations, yielding a significantly updated level scheme for $^{32}$Mg and spin-parity assignments. By fully exploiting observables obtained in this measurement, a variety of structures coexisting in 32Mg was unraveled. Comparisons with theoretical predictions based on shell-model overlaps allowed for clear discrimination between different structural models, revealing that the complete theoretical description of this key nucleus is yet to be achieved.